1. Field of the Invention
The present invention relates to a printing device, an information processing apparatus, a printing system, a signature verifying method, a signature adding method, and a program.
2. Description of the Related Art
Hitherto, in a network constructed of a plurality of host computers and printers, printer drivers of different versions have often been installed in the host computers. Also, when printers operate with the same printer language, but their types differ from each other, printer drivers adapted for the different types of printers have often been installed in the host computers. In such a situation, when print information produced by the printer drivers of different versions or by the printer drivers operating with the same printer language, but differing in type from each other is sent to the same printer, particularly when print information produced by a printer driver for a particular printer type is used in another type of printer for printing the produced print information, there may occur problems such as a printing failure, false rewriting of printer environment setting information, and rewriting of a font cache.
Japanese Patent Laid-Open No. 8-216481 discloses a technique to overcome those problems in a printer in which print information transferred from a printer driver in an external device is analyzed and a printing process is executed based on the analysis result. According to Japanese Patent Laid-Open No. 8-216481, the printer stores first management information for managing a printer main unit. On the other hand, second management information for identifying and managing a printer driver is embedded in print information produced by the printer driver. Then, the printer compares the second management information transferred from the printer driver in the external device with the first management information. If the second management information does not match with the first management information, the printer exercises control on a demand issued to the external device for the print information.
However, the known printer disclosed in Japanese Patent Laid-Open No. 8-216481 has problems as follows.
So long as the printer driver having produced the print information is one adapted for the relevant printer, that printer always starts operation to execute the printing process in accordance with the transferred print information. Therefore, even when the print information is received from a printer driver for which permission of use is not given by a system manager, for example, the printer starts operation to execute the printing process in accordance with the print information transmitted from that printer driver. The “printer driver for which permission of use is not given by a system manager” means, e.g., a printer driver that may cause a trouble in printing. If the printer driver for which permission of use is not given by the system manager is used, printing failure or other troubles may occur, thus necessitating an inquiry to the system manager or causing wasteful consumption of printer resources including sheets of paper.
Also, the following problem arises in a print network system wherein the system manager permits use of a particular printer driver for the purposes of security, billing, management of the number of printed sheets of paper, etc. For example, if a user obtains a printer driver for which permission of use is not given by the system manager and installs it in a host computer, printing can be performed with the installed printer driver without being subjected to the intended supervision, i.e., security, billing, management of the number of printed sheets of paper, etc.